scholarly journals The integration of activity in saline environments: problems and perspectives

2013 ◽  
Vol 40 (9) ◽  
pp. 759 ◽  
Author(s):  
John M. Cheeseman

The successful integration of activity in saline environments requires flexibility of responses at all levels, from genes to life cycles. Because plants are complex systems, there is no ‘best’ or ‘optimal’ solution and with respect to salt, glycophytes and halophytes are only the ends of a continuum of responses and possibilities. In this review, I briefly examine seven major aspects of plant function and their responses to salinity including transporters, secondary stresses, carbon acquisition and allocation, water and transpiration, growth and development, reproduction, and cytosolic function and ‘integrity’. I conclude that new approaches are needed to move towards understanding either organismal integration or ‘salt tolerance’, especially cessation of protocols dependent on sudden, often lethal, shock treatments and the embracing of systems level resources. Some of the tools needed to understand the integration of activity and even ‘salt stress’ are already in hand, such as those for whole-transcriptome analysis. Others, ranging from discovery studies of the nature of the cytosol to expanded tool kits for proteomic, metabolomic and epigenomic studies, still need to be further developed. After resurrecting the distinction between applied stress and the resultant strain and noting that with respect to salinity, the strain is manifest in changes at all -omic levels, I conclude that it should be possible to model and quantify stress responses.

Rice ◽  
2020 ◽  
Vol 13 (1) ◽  
Author(s):  
Xiang Zhang ◽  
Yan Long ◽  
Jingjing Huang ◽  
Jixing Xia

Abstract Background Salt stress threatens crop yields all over the world. Many NAC transcription factors have been reported to be involved in different abiotic stress responses, but it remains unclear how loss of these transcription factors alters the transcriptomes of plants. Previous reports have demonstrated that overexpression of OsNAC45 enhances salt and drought tolerance in rice, and that OsNAC45 may regulate the expression of two specific genes, OsPM1 and OsLEA3–1. Results Here, we found that ABA repressed, and NaCl promoted, the expression of OsNAC45 in roots. Immunostaining showed that OsNAC45 was localized in all root cells and was mainly expressed in the stele. Loss of OsNAC45 decreased the sensitivity of rice plants to ABA and over-expressing this gene had the opposite effect, which demonstrated that OsNAC45 played an important role during ABA signal responses. Knockout of OsNAC45 also resulted in more ROS accumulation in roots and increased sensitivity of rice to salt stress. Transcriptome sequencing assay found that thousands of genes were differently expressed in OsNAC45-knockout plants. Most of the down-regulated genes participated in plant stress responses. Quantitative real time RT-PCR suggested that seven genes may be regulated by OsNAC45 including OsCYP89G1, OsDREB1F, OsEREBP2, OsERF104, OsPM1, OsSAMDC2, and OsSIK1. Conclusions These results indicate that OsNAC45 plays vital roles in ABA signal responses and salt tolerance in rice. Further characterization of this gene may help us understand ABA signal pathway and breed rice plants that are more tolerant to salt stress.


Forests ◽  
2021 ◽  
Vol 12 (4) ◽  
pp. 413
Author(s):  
Qing Guo ◽  
Li Li ◽  
Kai Zhao ◽  
Wenjing Yao ◽  
Zihan Cheng ◽  
...  

SQUAMOSA promoter binding protein (SBP) is a kind of plant-specific transcription factor, which plays a crucial role in stress responses and plant growth and development by activating and inhibiting the transcription of multiple target genes. In this study, a total of 30 SBP genes were identified from Populus trichocarpa genome and randomly distributed on 16 chromosomes in poplar. According to phylogenetic analysis, the PtSBPs can be divided into six categories, and 14 out of the genes belong to VI. Furthermore, the SBP genes in VI were proved to have a targeting relationship with miR156. The homeopathic element analysis showed that the promoters of poplar SBP genes mainly contain the elements involved in growth and development, abiotic stress and hormone response. In addition, there existed 10 gene segment duplication events in the SBP gene duplication analysis. Furthermore, there were four poplar and Arabidopsis orthologous gene pairs among the poplar SBP members. What is more, poplar SBP gene family has diverse gene expression pattern under salt stress. As many as nine SBP members were responding to high salt stress and six members possibly participated in growth development and abiotic stress. Yeast two-hybrid experiments indicated that PtSBPs can form heterodimers to interact in the transcriptional regulatory networks. The genome-wide analysis of poplar SBP family will contribute to function characterization of SBP genes in woody plants.


2019 ◽  
Vol 60 (8) ◽  
pp. 1829-1841 ◽  
Author(s):  
Guochun Wu ◽  
Sha Li ◽  
Xiaochuan Li ◽  
Yunhong Liu ◽  
Shuangshuang Zhao ◽  
...  

Abstract Alternative oxidase (AOX) has been reported to be involved in mitochondrial function and redox homeostasis, thus playing an essential role in plant growth as well as stress responses. However, its biological functions in nonseed plants have not been well characterized. Here, we report that AOX participates in plant salt tolerance regulation in moss Physcomitrella patens (P. patens). AOX is highly conserved and localizes to mitochondria in P. patens. We observed that PpAOX rescued the impaired cyanide (CN)-resistant alternative (Alt) respiratory pathway in Arabidopsis thaliana (Arabidopsis) aox1a mutant. PpAOX transcription and Alt respiration were induced upon salt stress in P. patens. Using homologous recombination, we generated PpAOX-overexpressing lines (PpAOX OX). PpAOX OX plants exhibited higher Alt respiration and lower total reactive oxygen species accumulation under salt stress condition. Strikingly, we observed that PpAOX OX plants displayed decreased salt tolerance. Overexpression of PpAOX disturbed redox homeostasis in chloroplasts. Meanwhile, chloroplast structure was adversely affected in PpAOX OX plants in contrast to wild-type (WT) P. patens. We found that photosynthetic activity in PpAOX OX plants was also lower compared with that in WT. Together, our work revealed that AOX participates in plant salt tolerance in P. patens and there is a functional link between mitochondria and chloroplast under challenging conditions.


2021 ◽  
Vol 12 ◽  
Author(s):  
Pajaree Sonsungsan ◽  
Pheerawat Chantanakool ◽  
Apichat Suratanee ◽  
Teerapong Buaboocha ◽  
Luca Comai ◽  
...  

Salinity is an important environmental factor causing a negative effect on rice production. To prevent salinity effects on rice yields, genetic diversity concerning salt tolerance must be evaluated. In this study, we investigated the salinity responses of rice (Oryza sativa) to determine the critical genes. The transcriptomes of ‘Luang Pratahn’ rice, a local Thai rice variety with high salt tolerance, were used as a model for analyzing and identifying the key genes responsible for salt-stress tolerance. Based on 3' Tag-Seq data from the time course of salt-stress treatment, weighted gene co-expression network analysis was used to identify key genes in gene modules. We obtained 1,386 significantly differentially expressed genes in eight modules. Among them, six modules indicated a significant correlation within 6, 12, or 48h after salt stress. Functional and pathway enrichment analysis was performed on the co-expressed genes of interesting modules to reveal which genes were mainly enriched within important functions for salt-stress responses. To identify the key genes in salt-stress responses, we considered the two-state co-expression networks, normal growth conditions, and salt stress to investigate which genes were less important in a normal situation but gained more impact under stress. We identified key genes for the response to biotic and abiotic stimuli and tolerance to salt stress. Thus, these novel genes may play important roles in salinity tolerance and serve as potential biomarkers to improve salt tolerance cultivars.


2018 ◽  
Vol 19 (11) ◽  
pp. 3347 ◽  
Author(s):  
Yayun Wang ◽  
Hui Zhao ◽  
Hua Qin ◽  
Zixuan Li ◽  
Hai Liu ◽  
...  

The root plays an important role in the responses of plants to stresses, but the detailed mechanisms of roots in stress responses are still obscure. The GDP-mannose pyrophosphate synthetase (GMPase) OsVTC1-3 is a key factor of ascorbic acid (AsA) synthesis in rice roots. The present study showed that the transcript of OsVTC1-3 was induced by salt stress in roots, but not in leaves. Inhibiting the expression of OsVTC1-3 by RNA interfering (RI) technology significantly impaired the tolerance of rice to salt stress. The roots of OsVTC1-3 RI plants rapidly produced more O2−, and later accumulated amounts of H2O2 under salt stress, indicating the impaired tolerance of OsVTC1-3 RI plants to salt stress due to the decreasing ability of scavenging reactive oxygen species (ROS). Moreover, exogenous AsA restored the salt tolerance of OsVTC1-3 RI plants, indicating that the AsA synthesis in rice roots is an important factor for the response of rice to salt stress. Further studies showed that the salt-induced AsA synthesis was limited in the roots of OsVTC1-3 RI plants. The above results showed that specifically regulating AsA synthesis to scavenge ROS in rice roots was one of important factors in enhancing the tolerance of rice to salt stress.


PeerJ ◽  
2019 ◽  
Vol 7 ◽  
pp. e7291 ◽  
Author(s):  
Lei Wang ◽  
Wenjing Yao ◽  
Yao Sun ◽  
Jiying Wang ◽  
Tingbo Jiang

The WRKY transcription factor family is one of the largest groups of transcription factor in plants, playing important roles in growth, development, and biotic and abiotic stress responses. Many WRKY genes have been cloned from a variety of plant species and their functions have been analyzed. However, the studies on WRKY transcription factors in tree species under abiotic stress are still not well characterized. To understand the effects of the WRKY gene in response to abiotic stress, mRNA abundances of 102 WRKY genes in Populus simonii × P. nigra were identified by RNA sequencing under normal and salt stress conditions. The expression of 23 WRKY genes varied remarkably, in a tissue-specific manner, under salt stress. Since the WRKY56 was one of the genes significantly induced by NaCl treatment, its cDNA fragment containing an open reading frame from P. simonii × P. nigra was then cloned and transferred into Arabidopsis using the floral dip method. Under salt stress, the transgenic Arabidopsis over-expressed the WRKY56 gene, showing an increase in fresh weight, germination rate, proline content, and peroxidase and superoxide dismutase activity, when compared with the wild type. In contrast, transgenic Arabidopsis displayed a decrease in malondialdehyde content under salt stress. Overall, these results indicated that the WRKY56 gene played an important role in regulating salt tolerance in transgenic Arabidopsis.


Genes ◽  
2019 ◽  
Vol 10 (10) ◽  
pp. 742
Author(s):  
Nopphawitchayaphong Khrueasan ◽  
Panita Chutimanukul ◽  
Kitiporn Plaimas ◽  
Teerapong Buaboocha ◽  
Meechai Siangliw ◽  
...  

‘KDML105’ rice, known as jasmine rice, is grown in northeast Thailand. The soil there has high salinity, which leads to low productivity. Chromosome substitution lines (CSSLs) with the ‘KDML105’ rice genetic background were evaluated for salt tolerance. CSSL18 showed the highest salt tolerance among the four lines tested. Based on a comparison between the CSSL18 and ‘KDML105’ transcriptomes, more than 27,000 genes were mapped onto the rice genome. Gene ontology enrichment of the significantly differentially expressed genes (DEGs) revealed that different mechanisms were involved in the salt stress responses between these lines. Biological process and molecular function enrichment analysis of the DEGs from both lines revealed differences in the two-component signal transduction system, involving LOC_Os04g23890, which encodes phototropin 2 (PHOT2), and LOC_Os07g44330, which encodes pyruvate dehydrogenase kinase (PDK), the enzyme that inhibits pyruvate dehydrogenase in respiration. OsPHOT2 expression was maintained in CSSL18 under salt stress, whereas it was significantly decreased in ‘KDML105’, suggesting OsPHOT2 signaling may be involved in salt tolerance in CSSL18. PDK expression was induced only in ‘KDML105’. These results suggested respiration was more inhibited in ‘KDML105’ than in CSSL18, and this may contribute to the higher salt susceptibility of ‘KDML105’ rice. Moreover, the DEGs between ‘KDML105’ and CSSL18 revealed the enrichment in transcription factors and signaling proteins located on salt-tolerant quantitative trait loci (QTLs) on chromosome 1. Two of them, OsIRO2 and OsMSR2, showed the potential to be involved in salt stress response, especially, OsMSR2, whose orthologous genes in Arabidopsis had the potential role in photosynthesis adaptation under salt stress.


2016 ◽  
Vol 43 (7) ◽  
pp. 590 ◽  
Author(s):  
Yang Ping Lee ◽  
Christian Funk ◽  
Alexander Erban ◽  
Joachim Kopka ◽  
Karin I. Köhl ◽  
...  

Salinity strongly impairs plant growth and development. Natural genetic variation can be used to dissect complex traits such as plant salt tolerance. We used 16 accessions of the halophytic species Eutrema salsugineum (previously called Thellungiella salsuginea (Pallas) O.E.Schulz, Thellungiella halophila (C.A.Meyer) O.E. Schulz and Thellungiella botschantzevii D.A.German to investigate their natural variation in salinity tolerance. Although all accessions showed survival and growth up to 700 mM NaCl in hydroponic culture, their relative salt tolerance varied considerably. All accessions accumulated the compatible solutes proline, sucrose, glucose and fructose and the polyamines putrescine and spermine. Relative salt tolerance was not correlated with the content of any of the investigated solutes. We compared the metabolomes and transcriptomes of Arabidopsis thaliana (L. Heynh.) Col-0 and E. salsugineum Yukon under control and salt stress conditions. Higher content of several metabolites in Yukon compared with Col-0 under control conditions indicated metabolic pre-adaptation to salinity in the halophyte. Most metabolic salt responses in Yukon took place at 200 mM NaCl, whereas few additional changes were observed between 200 and 500 mM. The opposite trend was observed for the transcriptome, with only little overlap between salt-regulated genes in the two species. In addition, only about half of the salt-regulated Yukon unigenes had orthologues in Col-0.


Water ◽  
2019 ◽  
Vol 11 (8) ◽  
pp. 1667 ◽  
Author(s):  
Michael Santangeli ◽  
Concetta Capo ◽  
Simone Beninati ◽  
Fabrizio Pietrini ◽  
Cinzia Forni

Soil salinity is considered one of the most severe abiotic stresses in plants; plant acclimation to salinity could be a tool to improve salt tolerance even in a sensitive genotype. In this work we investigated the physiological mechanisms underneath the response to gradual and prolonged exposure to sodium chloride in cultivars of Brassica napus L. Fifteen days old seedlings of the cultivars Dynastie (salt tolerant) and SY Saveo (salt sensitive) were progressively exposed to increasing soil salinity conditions for 60 days. Salt exposed plants of both cultivars showed reductions of biomass, size and number of leaves. However, after 60 days the relative reduction in biomass was lower in sensitive cultivar as compared to tolerant ones. An increase of chlorophylls content was detected in both cultivars; the values of the quantum efficiency of PSII photochemistry (ΦPSII) and those of the electron transport rate (ETR) indicated that the photochemical activity was only partially reduced by NaCl treatments in both cultivars. Ascorbate peroxidase (APX) activity was higher in treated samples with respect to the controls, indicating its activation following salt exposure, and confirming its involvement in salt stress response. A gradual exposure to salt could elicit different salt stress responses, thus preserving plant vitality and conferring a certain degree of tolerance, even though the genotype was salt sensitive at the seed germination stage. An improvement of salt tolerance in B. napus could be obtained by acclimation to saline conditions.


2021 ◽  
Author(s):  
Kieu-Nga Tran ◽  
Guannan Wang ◽  
Dong-Ha Oh ◽  
John C. Larkin ◽  
Aaron P Smith ◽  
...  

Salinity stress is an ongoing problem for global crop production. Schrenkiella parvula and Eutrema salsugineum are salt-tolerant extremophytes closely related to Arabidopsis thaliana. We investigated multi-omics salt stress responses of the two extremophytes in comparison to A. thaliana. Our results reveal that S. parvula limits Na accumulation while E. salsugineum shows high tissue tolerance to excess Na. Despite this difference, both extremophytes maintained their nutrient balance, while A. thaliana failed to sustain its nutrient content. The root metabolite profiles of the two extremophytes, distinct at control conditions, converged upon prolonged salt stress. This convergence was achieved by a dynamic response in S. parvula roots increasing its amino acids and sugars to the constitutively high basal levels observed in E. salsugineum. The metabolomic adjustments were strongly supported by the transcriptomic responses in the extremophytes. The predominant transcriptomic signals in all three species were associated with salt stress. However, root architecture modulation mediated by negative regulators of auxin and ABA signaling supported minimally affected root growth unique to each extremophyte during salt treatments. Overall, E. salsugineum exhibited more preadapted responses at the metabolome level while S. parvula showed predominant pre-adaptation at the transcriptome level to salt stress. Our work shows that while salt tolerance in these two species shares common features, they substantially differ in pathways leading to convergent adaptive traits.


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